Three related problems of mevalonate metabolism and cholesterol biosynthesis are proposed for study. (I) It is known that mevalonate is not used exclusively for sterol biosynthesis, but that some metabolite derived from it is diverted to a pathway leading to contribution of carbon atoms to the C2-pool and that the kidneys play a key role in this "shunting" of mevalonate. It is proposed to examine and identify by enzymic, chromatographic and mass spectrometric techniques acid soluble and lipid soluble substances in kidneys and liver of rats injected intravenously with (R)-(5-14C) mevalonate. The identification of a new long-chain polyisoprenoid acid synthesized from mevalonate in every organ of the rat will be undertaken. (II) a) A detailed chemical characterization of liver prenyl transferase is proposed. Specifically the role of sulfhydryl groups in enzyme catalysis will be examined and also the hypothesis that the two forms of the enzyme represent different oxidation states of the enzyme. b) The binding of phenylglyoxal, found by us to inhibit the enzyme, will be examined specifically to determine whether arginine residues are involved in the inhibition. c) Kinetic studies of inhibition of prenyl transferase by phosphonophosphate analogues of geranyl pynophosphate will be undertaken. d) The solubilization and characterization of liver squalene synthetase will be examined. (III) The effects of chronic administration of mevalonate to rabbits on plasma mevalonate and lipoprotein levels will be studied by new micromethods.